soup: Drop transferMode.dlna.org header
soup: Drop transferMode.dlna.org header

Leave it to the application to decide on the header. No header at all
is better than having the wrong header as DLNA mandates that a missing
header has to be tolerated while a wrong header is an error.

https://bugzilla.gnome.org/show_bug.cgi?id=676020

freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good,freedesktop-unofficial-mirror/gstreamer-sdk__gst-plugins-good